migrate to environment files

See: https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#environment-files

Author: RobinMalfait

.github/workflows/release-insiders.yml

@@ -38,10 +38,10 @@ jobs:
 
       - name: Resolve version
         id: vars
-        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+        run: "sha_short=$(git rev-parse --short HEAD) >> $GITHUB_ENV"
 
-      - name: "Version based on commit: 0.0.0-insiders.${{ steps.vars.outputs.sha_short }}"
-        run: npm version 0.0.0-insiders.${{ steps.vars.outputs.sha_short }} --force --no-git-tag-version
+      - name: "Version based on commit: 0.0.0-insiders.${{ env.sha_short }}"
+        run: npm version 0.0.0-insiders.${{ env.sha_short }} --force --no-git-tag-version
 
       - name: Publish
         run: npm publish --tag insiders